How to solve median of a grouped data

Описание: How to construct a table for median of grouped data?
see this link how to solve the mode of a grouped data:
   • How to solve the mode of a grouped data?  
how to solve mean of a grouped data:
   • How to solve mean of a grouped data?  
How to solve median of a grouped data?
What is cumulative frequency? median class? frequency of median class? lower boundary or true lower limit of median class?